I was wondering whether any of the hot shots on here had any recommendations regarding how they keep track of their assets – specific software (?) vs. Excel – mainly stocks (historical and against various banks/brokers) but other categories would ideally be covered as well.

Ameritrade does that for me.
Otherwise, being financially lazy, update all asset data with private tax once a year.
But if a serious program is desired give gnuCash a try: https://www.gnucash.org/